Electrical power breakers often have a rotary contact system which has a fixed contact for connection to a current path, and also a rotatably mounted contact element which interacts with the fixed contact. The movable contact element, which is usually designed in the form of a bridge, serves to interrupt and to close the electrical circuit. An operating mechanism, for example in the form of a tilting lever, also called a handle, is used for manual connection and disconnection. In the event of a short circuit, the contact bridge is intended to open quickly due to electrodynamic forces, independently of the operating mechanism.
When the contact bridge is opened, a switch arc is produced between the contacts, said arc leading to a loss of material from the contacts, so-called contact erosion, at very high temperatures. The very hot, solid or gaseous contact-erosion products soil and/or damage the surfaces in the interior of the switch. This can have a considerable influence on the opening function of the switch and lead to production failures. Contact-erosion materials can also accumulate on the functional elements of the rotary contact system and prevent correct opening in the event of a short circuit owing to the resulting changing frictional conditions.
Electrical switches typically have a so-called quenching chamber. The switch arc is quenched in said quenching chamber, on which the movable contact and the stationary contact are arranged. So-called quenching plates, which are arranged around the arc such that they are electrically insulated from one another, are typically used to assist quenching. Contact-erosion materials can also accumulate between the quenching plates and lead to an electrical line between the plates, and this would reduce the effect of the plates on the arc on account of the electrical short circuit.